The present invention relates to an improved refractory composition and, more particularly, to a flexible thermally insulative refractory composition suitable for use for the containment of molten material.
In the foundry industry, molds and stools are used for the production of metal ingots wherein molten metal is poured into a mold essentially consisting of a base and side walls, the makeup of which provides resistance to molten metal attack. The mold contains the molten material and, after casting and solidifying in the mold, the cast metal is removed from the mold and cleaned to the desired finished product.
Heretofore, sand and, more recently, rigid, compressed, fibrous, silica-alumina boards have been used to form the base and side walls of a metal mold and stool. One of the objects of the present invention is to provide a refractory composition that can be used to replace the sand and rigid, compressed, fibrous, silica-alumina boards. Accordingly, herein is provided a flexible thermally insulative refractory composition suitable for use in the foundry industry to contain molten metal.
The prior art above-mentioned rigid board, while sufficient for use as the base of a mold stool, has severe shortcomings when it is used as a mold or stool side wall, particularly when a rounded edge or rounded corner is encountered or desired. Use of rigid board to round an edge or corner would require scoring of the board at several places along the board at the location of a curve to be followed to give the board the needed flexibility for shaping to follow the desired path. Use of a rigid board to follow or form a curve requires additional labor to score the board thus increasing labor and overall installation costs. Additionally, scoring results in undesirable ingot surface imperfections which require additional labor for removal. However, the most severe problem associated with board scoring is the creation of seams along the curve. The seams so created form weak points along the wall that often allow undesirable metal penetration leading to metal loss, metal contamination, irregular product shape, shortening mold use life, and potential hazard to health.
The present invention overcomes many of the shortcomings of the prior art rigid board. The refractory composition of the present invention is flexible, having a bend radius of at least 3 inches, and therby eliminates the need for scoring to round an edge or follow a curve. Use of the inventive flexible composition provides for fewer mold seams, reduces labor costs, affords greater ease in installation, and virtually eliminates metal penetration along curved surfaces.